Haematology

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Serum folate assay is now performed on the Abbott Alinity platform as of 10th September 2024.

Patient must be fasting for a minimum of 12hrs for B12/folate testing

Queries to Haematinics Laboratory on 01-4162012

See GP External Request Form for B12 and Folate. This form must be filled in completely. When requesting blood tests for patients, place all extra forms (e.g. for B12/Folate and Vit D) and necessary samples in the same bag to allow easier processing of patient samples on receipt in laboratory.

All Forms found here:

https://www.stjames.ie/services/laboratorymedicinelabmed/policiesandguidelines/gpexternalrequestforms/

Haematinics Demand Management Guidelines:

1. Patients on parenteral vitamin B12 or oral folic acid replacement therapy should not have further vitamin B12 or folic acid measurements performed unless blood counts or neurological symptoms fail to improve.

2. Repeating normal vitamin B12 levels is rarely indicated within 6 months of testing.

3. Repeating normal folate levels is rarely indicated within 3 months of testing.

4. Clinical details are required for all B12 and folate requests.

Limitations of the assay:

• Haemolysed serum samples are unacceptable for analysis and give falsely raised folate results. 
• Specimens from patients who have received preparations of mouse monoclonal antibodies for diagnosis or therapy may contain human anti-mouse antibodies (HAMA). Such specimens may show either falsely elevated or depressed values when tested with assay kits such as Alinity i Folate that employ mouse monoclonal antibodies. Additional information may be required for diagnosis.
• Heterophilic antibodies in human serum can react with reagent immunoglobulins, interfering with in vitro immunoassays. Patients routinely exposed to animals or to animal serum products can be prone to this interference, and anomalous values may be observed. Additional information may be required for diagnosis.
• Samples to be tested for folate should be protected from light. Light accelerates the degradation of folate.
• Serum and plasma specimens from patients with renal impairment or failure (including dialysis patients) may exhibit varying degrees of falsely depressed folate values. Therefore, additional information may be required for diagnosis.
• Methotrexate, aminopterin, and folinic acid (Leucovorin) are chemotherapeutic agents whose molecular structures are similar to folate. These agents cross react with folate binding protein in folate assays.

Related links

Folate, with vitamin B12, is essential for DNA synthesis, which is required for normal red blood cell maturation. Humans obtain Folate from dietary sources including fruits, green and leafy vegetables, yeast, and organ meats. Folate is absorbed through the small intestine and stored in the liver.

Low folate intake, malabsorption as a result of gastrointestinal diseases, pregnancy, and drugs such as phenytoin are causes of Folate deficiency. Folate deficiency is also associated with chronic alcoholism. Folate and vitamin B12 deficiency impair DNA synthesis, causing macrocytic anaemias. These anaemias are characterised by abnormal maturation of red blood cell precursors in the bone marrow, the presence of megaloblasts, and decreased red blood cell survival.

Since both Folate and vitamin B12 deficiency can cause macrocytic anaemia, appropriate treatment depends on the differential diagnosis of the deficiency. Serum Folate measurement provides an early index of Folate status. 

Reference range

Please note new reference range from 10th September 2024.

3.8 -18.2 ug/l

Last updated

Fri, 23 Jan 2026 08:29:05 GMT